package com.leo.book.netty.chapter02;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;
import java.util.Set;

public class NIOTimeServer {
	
	public static void main(String[] args) throws IOException {
		int port = 8080;
		if (args!=null && args.length>0) {
			try {
				port = Integer.valueOf(args[0]);
			} catch (NumberFormatException e) {
				//
			}
		}
		MultiplexerTimeServer timeServer = new MultiplexerTimeServer(port);
		new Thread(timeServer, "NIO-MultiplexerTimeServer-001").start();
	}
}

class MultiplexerTimeServer implements Runnable {
	private Selector selector;
	private ServerSocketChannel serverSocketChannel;
	private volatile boolean stop;
	
	public MultiplexerTimeServer(int port) {
		try{
			selector = Selector.open();
			serverSocketChannel = ServerSocketChannel.open();
			serverSocketChannel.configureBlocking(false);
			serverSocketChannel.socket().bind(new InetSocketAddress(port), 1024);
			serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
			System.out.println("The time server is start in port: "+port);
		}catch(IOException e){
			e.printStackTrace();
			System.exit(1);
		}
	}
	
	public void stop() {
		this.stop = true;
	}
	
	@Override
	public void run() {
		while(!stop) {
			try{
				selector.select(1000);
				Set<SelectionKey> selectedKeys = selector.selectedKeys();
				Iterator<SelectionKey> it = selectedKeys.iterator();
				SelectionKey key = null;
				while (it.hasNext()) {
					key = it.next();
					it.remove();
					try{
						handleInput(key);
					}catch(IOException e){
						if(key!=null){
							key.cancel();
							if(key.channel()!=null)
								key.channel().close();
						}
					}
				}
			}catch(Throwable t) {
				t.printStackTrace();
			}
		}
		if(selector!=null) {
			try{
				selector.close();
			}catch(IOException e) {
				e.printStackTrace();
			}
		}
	}
	
	private void handleInput(SelectionKey key) throws IOException {
		if(key.isValid()){
			if(key.isAcceptable()){
				ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
				SocketChannel sc = ssc.accept();
				sc.configureBlocking(false);
				sc.register(selector, SelectionKey.OP_READ);
			}
			if(key.isReadable()){
				SocketChannel sc = (SocketChannel)key.channel();
				ByteBuffer readBuffer = ByteBuffer.allocate(1024);
				int readBytes = sc.read(readBuffer);
				if(readBytes>0){
					readBuffer.flip();
					byte[] bytes = new byte[readBuffer.remaining()];
					readBuffer.get(bytes);
					String body = new String(bytes, "UTF-8");
					System.out.println("The time server receive order: "+body);
					String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? 
						new Date(System.currentTimeMillis()).toString() : "BAD ORDER";
					doWrite(sc, currentTime);
				} else if(readBytes<0){
					key.cancel();
					sc.close();
				} else {
					//
				}
			}
		}
	}
	
	private void doWrite(SocketChannel channel, String response)throws IOException {
		if(response!=null && response.trim().length()>0) {
			byte[] bytes = response.getBytes();
			ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
			writeBuffer.put(bytes);
			writeBuffer.flip();
			channel.write(writeBuffer);
		}
	}
}